Enhanced THz EIT resonance based on the coupled electric field dropping effect within the undulated meta-surface

Lan Wang,Xinlan Zhou,Ziqiang Yang,Hongxin Zeng,Ping Zhang,Feng Lan,Lin Yuan,Ting Zhang,Xiaoqing Guo,Shixiong Liang,Yaxin Zhang,Wei Kou

doi:10.1515/nanoph-2019-0040

Abstract

Abstract In this paper, the enhanced terahertz (THz) electromagnetically induced transparency (EIT) resonance is achieved based on the coupled electric field dropping effect within the undulated meta-surface. It is found that the height difference between the inner ring and the outer split ring could lead to a significant coupled mode with electric field dropping distribution. When the height of the inner ring increases, the electric field of the inner ring gradually cascades to the outer ring just as a waterfall so that the coupling between the two rings in a unit cell and two adjacent units is enhanced. Both the simulation and experimental results show that a nearly 95% transparency window which is twice that of traditional EIT can be observed by applying such coupled electric field dropping effect, which may provide a promising way to develop the high resonance intensity meta-surface in the THz region.

Highlights

electromagnetically induced transparency (EIT) is the quantum destructive interference in a threelevel atomic system, leading to an extremely narrowband transparency window over a wide absorption spectrum [1]
In this paper, the enhanced terahertz (THz) electromagnetically induced transparency (EIT) resonance is achieved based on the coupled electric field dropping effect within the undulated meta-surface
Recent studies have shown that the EIT effect can be mimicked by a series of classical optical systems, such as on-chip plasmonic structures [2], photonic crystals [3,4,5] and meta-surfaces [6,7,8,9,10]

Summary

Introduction

EIT is the quantum destructive interference in a threelevel atomic system, leading to an extremely narrowband transparency window over a wide absorption spectrum [1]. Apart from its fundamental significance, meta-surface-induced transparency in subwavelength structures is the most recent and promising addition to the existing classical EIT schemes [11,12,13] Terahertz bandpass devices, such as the THz modulators and sensing devices [14], have been developed by applying the transparency window of the EIT. Both the theoretical and experimental results show that the transmission of the EIT transparency window could be nearly doubled under 20 times height difference Such a coupled electric field dropping effect may provide a promising way to develop the high resonance intensity meta-surface in the THz region

The mechanism of the coupled electric field dropping effect

Theory and numerical calculation of the coupling EIT resonance

Findings

Experimental design and measurement